8.5 W VECSEL output at 1270 nm with conversion efficiency of 59%

We report on 1270 nm vertical-external-cavity surface-emitting lasers (VECSELs) with up to 59% conversion efficiency and maximum output power of 8.5 W (pump limited), at 5°C heat sink temperature. These VECSELs comprised wafer-fused gain mirrors in the flip-chip (thin-disk) heat dissipation scheme. The reflected pump light from the gain mirror surface was found to depend considerably on temperature and pump power.